Scale-type nonconstrained health condition evaluating apparatus and method

ABSTRACT

A scale-type nonconstrained health condition evaluating apparatus includes a load cell sensor for sensing a ballistocardiogram signal and a weight signal from a measured person, an electrocardiogram sensor for sensing an electrocardiogram signal from the measured person, and a signal processor for calculating at least one of the heart rate, normalized stroke volume force, blood pressure and equilibrium sense abnormality of the measured person from the ballistocardiogram, weight and electrocardiogram signals sensed by the load cell sensor and the electrocardiogram sensor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a scale-type nonconstrained healthcondition evaluating apparatus and method, and more particularly, to ascale-type nonconstrained health condition evaluating apparatus andmethod for measuring electrocardiogram, ballistocardiogram and weightsignals from a measured person in a nonconstrained manner, calculatingat least one of the heart rate, normalized stroke volume force, bloodpressure and equilibrium sense abnormality of the measured person fromthe measured signals and outputting the calculation result.

2. Background of the Related Art

As widely known, cardiovascular disorders such as myocardial infarction,angina pectoris, cardiac failure, arteriosclerosis, embolism,hypertension, atherosclerosis and thrombus frequently occur in highlyindustrialized countries and become the biggest cause of death togetherwith cancers and cerebrovascular disorders in advanced countries.

Recently, cardiovascular disorders have increased in Korea as incomelevels of people increase and food, closing and housing environmentsbecome westernized. Accordingly, a device for monitoring cardiovascularstates of people only through simple measurement at home and indoors isrequired. However, conventional health devices adopt a method of flowingcurrent to a measured person to measure the health condition of theperson, and thus the devices may have bad influence on the body of themeasured person and have limitations in providing information sufficientfor monitoring cardiovascular disorders.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made in view of theabove-mentioned problems occurring in the prior art, and it is a primaryobject of the present invention to provide a scale-type nonconstrainedhealth condition evaluating apparatus and method for measuring anelectrocardiogram signal, a ballistocardiogram signal and a weightsignal from a measured person in a nonconstrained manner, calculating atleast one of the heart rate, normalized stroke volume force, bloodpressure and equilibrium sense abnormality of the measured person fromthe measured signals and outputting the calculation result.

To accomplish the above object of the present invention, according tothe present invention, there is provided a scale-type nonconstrainedhealth condition evaluating apparatus comprising a load cell sensor forsensing a ballistocardiogram signal and a weight signal from a measuredperson; an electrocardiogram sensor for sensing an electrocardiogramsignal from the measured person; and a signal processor for calculatingat least one of the heart rate, normalized stroke volume force, bloodpressure and equilibrium sense abnormality of the measured person fromthe ballistocardiogram, weight and electrocardiogram signals sensed bythe load cell sensor and the electrocardiogram sensor.

The scale-type nonconstrained health condition evaluating apparatus mayfurther comprise a display that outputs the heart rate, normalizedstroke volume force, blood pressure or equilibrium sense abnormality ofthe measured person, calculated by the signal processor.

The electrocardiogram sensor may include two bar-shaped exposedelectrocardiogram electrodes and measure the electrocardiogram signalfrom both hands of the measured person. Otherwise, the electrocardiogramsensor may include two electrocardiogram electrodes that are attached tothe top face of the load cell sensor to measure the electrocardiogramsignal from both feet of the measured person.

The signal processor may comprise a signal amplifier for amplifying theballistocardiogram and electrocardiogram signals sensed by the load cellsensor and the electrocardiogram sensor; a band pass filter forfiltering only necessary bands of the ballistocardiogram andelectrocardiogram signals amplified by the signal amplifier; an A/Dconverter for converting the ballistocardiogram and electrocardiogramsignals filtered by the band pass filter into digital signals; and acomputing unit for calculating at least one of the heart rate,normalized stroke volume force, blood pressure and equilibrium senseabnormality of the measured person from the weight of the measuredperson, sensed by the load cell sensor, the ballistocardiogram andelectrocardiogram signals converted into the digital signals by the A/Dconverter.

The band pass filter may filter only 0.5 through 30 Hz components of theballistocardiogram signal amplified by the signal amplifier and filteronly 0.5 through 35 Hz components of the electrocardiogram signalamplified by the signal amplifier.

The computing unit may detect J waves from the ballistocardiogram signalconverted by the A/D converter into the digital signal and calculate aninterval of the J waves to obtain an average heart rate of the measuredperson.

The computing unit may synchronize the electrocardiogram signal with theballistocardiogram signal based on the J waves of the ballistocardiogramsignal to obtain an ensemble average so as to generate averagedelectrocardiogram and ballistocardiogram signals, obtain the magnitudeof the J waves from the averaged ballistocardiogram signal and calculatethe normalized stroke volume force of the measured person according tothe following equation.

Normalized stroke volume force=J-wave magnitude/weight.

The computing unit may detect an R-J interval from the averagedballistocardiogram and electrocardiogram signals and calculate the bloodpressure of the measured person from a regression equation derived fromdata about correlation of the R-J interval and a systolic bloodpressure.

The computing unit may measure the extent of a variation of theballistocardiogram signal and determine whether the sense of equilibriumof the measured person is abnormal from the measurement result.

The signal processor may identify the measured person through at leastone of the calculated heart rate, normalized stroke volume force, bloodpressure, equilibrium sense abnormality and weight of the measuredperson.

To accomplish the above object of the present invention, according tothe present invention, there is provided a method for evaluating thehealth condition of a measured person in a scale-type nonconstrainedhealth condition evaluating apparatus, which comprises a first step ofsensing ballistocardiogram and weight signals from the measured person;a second step of sensing an electrocardiogram signal from the measuredperson; and a third step of calculating at least one of the heart rate,normalized stroke volume force, blood pressure and equilibrium senseabnormality of the measured person from the sensed ballistocardiogram,weight and electrocardiogram signals.

The method may further comprise the step of outputting the calculatedheart rate, normalized stroke volume force, blood pressure orequilibrium sense abnormality after the third step.

The third step may comprise the steps of amplifying the sensedballistocardiogram and electrocardiogram signals; filtering onlynecessary bands of the amplified ballistocardiogram andelectrocardiogram signals; converting the filtered ballistocardiogramand electrocardiogram signals into digital signals; and calculating atleast one of the heart rate, normalized stroke volume force, bloodpressure and equilibrium sense abnormality of the measured person fromthe weight of the measured person and the ballistocardiogram andelectrocardiogram signals converted into the digital signals.

To accomplish the above object of the present invention, according tothe present invention, there is provided a method for calculating theblood pressure of a measured person by using an R-J interval, whichcomprises a first step of detecting the R-J interval fromballistocardiogram and electrocardiogram signals measured from themeasured person and a second step of calculating the blood pressure ofthe measured person according to a regression equation derived from dataabout correlation of the R-J interval and a systolic blood pressure.

The first steps may comprises the steps of detecting J waves from theballistocardiogram signal; synchronizing the electrocardiogram signalwith the ballistocardiogram signal based on the detected J waves of theballistocardiogram signal to obtain an ensemble average to as togenerate averaged electrocardiogram and ballistocardiogram signals; anddetecting the R-J interval from the averaged electrocardiogram andballistocardiogram signals.

As described above, the present invention can easily monitor thecardiovascular health condition of a measured person at home and indoorsall the time by using the scale-type apparatus. Furthermore, the healthcondition evaluating apparatus can safely measure the health conditionbecause it uses a nonconstrained method that does not flow current tothe measured person and only measures a vital signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be apparent from the following detailed description ofthe preferred embodiments of the invention in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a scale-type nonconstrained health conditionevaluating apparatus according to a first embodiment of the presentinvention;

FIG. 2 illustrates a scale-type nonconstrained health conditionevaluating apparatus according to a second embodiment of the presentinvention;

FIG. 3 is a block diagram of the scale-type nonconstrained healthcondition evaluating apparatus according to the present invention.

FIG. 4 is a flowchart of a nonconstrained health condition evaluatingmethod according to the present invention;

FIG. 5 illustrates an electrocardiogram signal and a ballistocardiogramsignal measured according to the present invention;

FIG. 6 illustrates averaged electrocardiogram and ballistocardiogramsignals obtained through an ensemble average;

FIG. 7 is a graph illustrating a variation in R-J interval of a measuredperson when valsalva maneuver is performed;

FIG. 8 is a graph illustrating correlation of an R-J interval and asystolic blood pressure; and

FIG. 9 is a graph illustrating a ballistocardiogram signal and varianceof the ballistocardiogram signal according to a situation of a measuredperson.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more fully with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown. The invention may, however, be embodied in manydifferent forms and should not be construed as being limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the concept of the invention to those skilled in the art.

FIG. 1 illustrates a scale-type nonconstrained health conditionevaluating apparatus 100 according to a first embodiment of the presentinvention.

Referring to FIG. 1, the scale-type nonconstrained health conditionevaluating apparatus 100 includes a load cell sensor 110, anelectrocardiogram sensor 120 and a display 140.

The load cell sensor 110 is located under the feet of a standingmeasured person. The load cell sensor 110 may be placed under the hipsof the measured person when he or she sits and located under the chestof the measured person when he or she lies down. The weight of theperson can be measured from a weight signal measured by the load cellsensor 110 and the weight signal can be amplified and filtered by asignal processor 130, which will be explained later, to obtain aballistocardiogram signal according to a variation in the cardiovascularstate of measured the person.

The electrocardiogram sensor 120 includes two bar-shaped exposedelectrocardiogram electrodes that come in contact with the palms of themeasured person to measure the electrocardiogram of the person.

The functions and detailed configurations of the load cell sensor 110,the electrocardiogram sensor 120 and the display 140 will be explainedin detail with reference to FIG. 3.

FIG. 2 a scale-type nonconstrained health condition evaluating apparatus100′ according to a second embodiment of the present invention.

Referring to FIG. 2, the scale-type nonconstrained health conditionevaluating apparatus 100′ has an electrocardiogram sensor 120′ locatedin a position different from that of the scale-type nonconstrainedhealth condition evaluating apparatus 100 according to the firstembodiment of the present invention. Specifically, two electrocardiogramelectrodes of the electrocardiogram sensor 120′ are attached to the topface of the load cell sensor 110 to measure an electrocardiogram signalfrom both feet of the measured person.

FIG. 3 is a block diagram of the scale-type nonconstrained healthcondition evaluating apparatus according to the present invention.

Referring to FIG. 3, the scale-type nonconstrained health conditionevaluating apparatus according to the present invention includes theload cell sensor 110, the electrocardiogram sensor 120, the signalprocessor 130, and the display 140.

The load cell sensor 110 measures a ballistocardiogram signals and aweight signal from a measured person. The electrocardiogram sensor 120measures an electrocardiogram signal from the measured person and may beconstructed in such a manner that the electrocardiogram signal ismeasured from the hands or feet of the measured person, as describedabove.

The signal processor 130 calculates at least one of the heart rate,normalized stroke volume force, blood pressure and equilibrium senseabnormality of the measured person from the ballistocardiogram, weightand electrocardiogram signals measured by the load cell sensor 110 andthe electrocardiogram sensor 120.

The display 140 outputs information on the at least one of the heartrate, normalized stroke volume force, blood pressure and equilibriumsense abnormality calculated by the signal processor 130 in a formrecognizable by the sense of sight and hearing of the measured person.

The signal processor 130 will now be explained in more detail. Thesignal processor 130 includes a signal amplifier 131, a band pass filter132, an A/D converter 133 and a computing unit 134.

The signal amplifier 131 amplifies the ballistocardiogram andelectrocardiogram signals sensed by the load cell sensor 110 and theelectrocardiogram sensor 120.

The band pass filter 132 filters only necessary bands of theballistocardiogram and electrocardiogram signals amplified by the signalamplifier 131.

More specifically, the band pass filter 132 filters 0.5 through 30 Hzcomponents of the amplified ballistocardiogram signal and filters 0.5through 35 Hz components of the amplified electrocardiogram signal.

The A/D converter 133 converts the ballistocardiogram andelectrocardiogram signals filtered by the band pass filter 132 into 1kHZ and 16-bit digital signals.

The computing unit 134 calculates at least one of the heart rate,normalized stroke volume force, blood pressure and equilibrium senseabnormality of the measured person from the weight of the person, sensedby the load cell sensor 110, the ballistocardiogram andelectrocardiogram signals converted into the digital signals by the A/Dconverter 133.

FIG. 4 is a flowchart of a nonconstrained health condition evaluatingmethod according to the present invention.

A ballistocardiogram signal, an electrocardiogram signal and the weightof a measured person are sensed by the load cell sensor 110 and theelectrocardiogram sensor 120 in step S401. The sensed ballistocardiogramand electrocardiogram signals are amplified and necessary bands thereofare filtered through the signal processor 130. Then, the filteredsignals are converted into digital signals in steps S402, S403 and S404.FIG. 5 illustrates the ballistocardiogram and electrocardiogram signalsconverted into the digital signals through the aforementioned operation.

Subsequently, J waves are detected from the digital ballistocardiogramsignal in step S405 and an interval of the J waves is calculated toobtain an average hear rate of the measured person in step S406.

Furthermore, a normalized stroke volume force and an average bloodpressure of the measured person can be obtained from the digitalballistocardiogram and electrocardiogram signals.

When the electrocardiogram signal is synchronized withballistocardiogram signal based on the J waves of the ballistocardiogramsignal, which are detected in step S405, to obtain an ensemble averagein step S407, averaged ballistocardiogram and electrocardiogram signalsfrom which an error due to a motion of the measured person orelectrostatic noise has been removed can be obtained, as illustrated inFIG. 6. FIG. 6 illustrates the averaged ballistocardiogram andelectrocardiogram signals obtained through the aforementioned operation.

When the magnitude of the J waves, which increases in proportion tocardiaoutput generated for a single stroke, is obtained from theaveraged ballistocardiogram signal calculated in step S407 and dividedby the weight according to the following equation, the normalized strokevolume force can be obtained in step S408.

Normalized stroke volume force-J-wave magnitude/weight

A step of obtaining the blood pressure of the measured person will nowbe explained.

An R-J interval is detected from the averaged ballistocardiogram andelectrocardiogram signals, which are calculated in step S407, in stepS409.

The R-J interval reflects a cardiovascular state varied according tovalsalva maneuver or other stimuli. For example, the R-J interval of themeasured person increases when the valsalva maneuver is performed, asillustrated in FIG. 7.

Correlation of the R-J interval and a systolic blood pressure is asillustrated in FIG. 8 and correlation coefficient thereof is 0.73.Accordingly, if an expression that represents the correlation of the R-Jinterval and the systolic blood pressure is obtained using a linearregression equation, it is possible to calculate the blood pressure ofthe measured person by using only the R-J interval according to thefollowing equation in step S410.

SBP(n)=−803.6091×RJI(n)+349.6055

Here, SBP(n) represents an average blood pressure for n stokes of themeasured person and RJI(n) denotes an average R-J interval.

The extent of a variation of the measured ballistocardiogram signal canbe measured to determine how much the measured person stands in astabilized pose and it is possible to check whether the equilibriumsensory organ of the measured person is abnormal by using thedetermination result in step S411.

FIG. 9 the ballistocardiogram signal and variance of theballistocardiogram signal when the measured person stands on the loadcell sensor, when the measured person moves the center of gravity of thebody to the left and right, when the measured person moves the center ofgravity of the body back and forth, and when the person closes his orher eyes and tries to maintain equilibrium. It can be known from FIG. 9that the variance of the ballistocardiogram signal increases when thebody of the person moves. Accordingly, it is possible to evaluate theextent of unstable motion over the entire test section.

The weight of the measured person can be measured from an unprocessedweight signal output from the load cell sensor 110 in step S412.

Furthermore, measured persons can be identified by using at least one ofthe heart rate, normalized stroke volume force, blood pressure,equilibrium sense abnormality and weight of each of the measured personsin an environment in which members of a family or ten constituentmembers or less use the scale-type nonconstrained health conditionevaluating apparatus according to the present invention.

The information on the heart rate, normalized stroke volume force, bloodpressure, equilibrium sense abnormality and weight of the measuredperson, which are calculated through the aforementioned operations, isoutput through the display in a form recognizable by the sense of sightand hearing of the measured person in step 413.

While the present invention has been described with reference to theparticular illustrative embodiments, it is not to be restricted by theembodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentswithout departing from the scope and spirit of the present invention.

1. A scale-type nonconstrained health condition evaluating apparatuscomprising: a load cell sensor for sensing a ballistocardiogram signaland a weight signal from a measured person; an electrocardiogram sensorfor sensing an electrocardiogram signal from the measured person; and asignal processor for calculating at least one of the heart rate,normalized stroke volume force, blood pressure and equilibrium senseabnormality of the measured person from the ballistocardiogram, weightand electrocardiogram signals sensed by the load cell sensor and theelectrocardiogram sensor.
 2. The scale-type nonconstrained healthcondition evaluating apparatus according to claim 1, further comprisinga display that outputs the heart rate, normalized stroke volume force,blood pressure or equilibrium sense abnormality of the measured person,calculated by the signal processor.
 3. The scale-type nonconstrainedhealth condition evaluating apparatus according to claim 1, wherein theelectrocardiogram sensor includes two bar-shaped exposedelectrocardiogram electrodes and measures the electrocardiogram signalfrom both hands of the measured person.
 4. The scale-type nonconstrainedhealth condition evaluating apparatus according to claim 1, wherein theelectrocardiogram sensor includes two electrocardiogram electrodes thatare attached to the top face of the load cell sensor to measure theelectrocardiogram signal from both feet of the measured person.
 5. Thescale-type nonconstrained health condition evaluating apparatusaccording to claim 1, wherein the signal processor comprises: a signalamplifier for amplifying the ballistocardiogram and electrocardiogramsignals sensed by the load cell sensor and the electrocardiogram sensor;a band pass filter for filtering only necessary bands of theballistocardiogram and electrocardiogram signals amplified by the signalamplifier; an A/D converter for converting the ballistocardiogram andelectrocardiogram signals filtered by the band pass filter into digitalsignals; and a computing unit for calculating at least one of the heartrate, normalized stroke volume force, blood pressure and equilibriumsense abnormality of the measured person from the weight of the measuredperson, sensed by the load cell sensor, the ballistocardiogram andelectrocardiogram signals converted into the digital signals by the A/Dconverter.
 6. The scale-type nonconstrained health condition evaluatingapparatus according to claim 5, wherein the band pass filter filtersonly 0.5 through 30 Hz components of the ballistocardiogram signalamplified by the signal amplifier.
 7. The scale-type nonconstrainedhealth condition evaluating apparatus according to claim 5, wherein theband pass filter filters only 0.5 through 35 Hz components of theelectrocardiogram signal amplified by the signal amplifier.
 8. Thescale-type nonconstrained health condition evaluating apparatusaccording to claim 5, wherein the computing unit detects J waves fromthe ballistocardiogram signal converted by the A/D converter into thedigital signal and calculates an interval of the J waves to obtain anaverage heart rate of the measured person.
 9. The scale-typenonconstrained health condition evaluating apparatus according to claim5, wherein the computing unit synchronizes the electrocardiogram signalwith the ballistocardiogram signal based on the J waves of theballistocardiogram signal to obtain an ensemble average so as togenerate averaged electrocardiogram and ballistocardiogram signals. 10.The scale-type nonconstrained health condition evaluating apparatusaccording to claim 9, wherein the computing unit obtains the magnitudeof the J waves from the averaged ballistocardiogram signal andcalculates the normalized stroke volume force of the measured personaccording to the following equation:Normalized stroke volume force=J-wave magnitude/weight
 11. Thescale-type nonconstrained health condition evaluating apparatusaccording to claim 9, wherein the computing unit detects an R-J intervalfrom the averaged ballistocardiogram and electrocardiogram signals andcalculates the blood pressure of the measured person from a regressionequation derived from data about correlation of the R-J interval and asystolic blood pressure.
 12. The scale-type nonconstrained healthcondition evaluating apparatus according to claim 5, wherein thecomputing unit measures the extent of a variation of theballistocardiogram signal and determines whether the sense ofequilibrium of the measured person is abnormal from the measurementresult.
 13. The scale-type nonconstrained health condition evaluatingapparatus according to claim 1, wherein the signal processor identifiesthe measured person through at least one of the calculated heart rate,normalized stroke volume force, blood pressure, equilibrium senseabnormality and weight of the measured person.
 14. A method forevaluating the health condition of a measured person in a scale-typenonconstrained health condition evaluating apparatus, the methodcomprising: sensing ballistocardiogram and weight signals from themeasured person; sensing an electrocardiogram signal from the measuredperson; and calculating at least one of the heart rate, normalizedstroke volume force, blood pressure and equilibrium sense abnormality ofthe measured person from the sensed ballistocardiogram, weight andelectrocardiogram signals.
 15. The method according to claim 14, furthercomprising outputting the calculated heart rate, normalized strokevolume force, blood pressure or equilibrium sense abnormality after thecalculating at least one of the heart rate.
 16. The method according toclaim 14, wherein the calculating at least one of the heart ratecomprises: amplifying the sensed ballistocardiogram andelectrocardiogram signals; filtering only necessary bands of theamplified ballistocardiogram and electrocardiogram signals; convertingthe filtered ballistocardiogram and electrocardiogram signals intodigital signals; and calculating at least one of the heart rate,normalized stroke volume force, blood pressure and equilibrium senseabnormality of the measured person from the weight of the measuredperson and the ballistocardiogram and electrocardiogram signalsconverted into the digital signals.
 17. A method for calculating theblood pressure of a measured person by using an R-J interval, the methodcomprising: detecting the R-J interval from ballistocardiogram andelectrocardiogram signals measured from the measured person; andcalculating the blood pressure of the measured person according to aregression equation derived from data about correlation of the R-Jinterval and a systolic blood pressure.
 18. The method according toclaim 17, wherein the detecting the R-J interval comprises: detecting Jwaves from the ballistocardiogram signal; synchronizing theelectrocardiogram signal with the ballistocardiogram signal based on thedetected J waves of the ballistocardiogram signal to obtain an ensembleaverage to as to generate averaged electrocardiogram andballistocardiogram signals; and detecting the R-J interval from theaveraged electrocardiogram and ballistocardiogram signals.
 19. Thescale-type nonconstrained health condition evaluating apparatusaccording to claim 2, wherein the electrocardiogram sensor includes twobar-shaped exposed electrocardiogram electrodes and measures theelectrocardiogram signal from both hands of the measured person.
 20. Thescale-type nonconstrained health condition evaluating apparatusaccording to claim 2, wherein the electrocardiogram sensor includes twoelectrocardiogram electrodes that are attached to the top face of theload cell sensor to measure the electrocardiogram signal from both feetof the measured person.
 21. The scale-type nonconstrained healthcondition evaluating apparatus according to claim 2, wherein the signalprocessor comprises: a signal amplifier for amplifying theballistocardiogram and electrocardiogram signals sensed by the load cellsensor and the electrocardiogram sensor; a band pass filter forfiltering only necessary bands of the ballistocardiogram andelectrocardiogram signals amplified by the signal amplifier; an A/Dconverter for converting the ballistocardiogram and electrocardiogramsignals filtered by the band pass filter into digital signals; and acomputing unit for calculating at least one of the heart rate,normalized stroke volume force, blood pressure and equilibrium senseabnormality of the measured person from the weight of the measuredperson, sensed by the load cell sensor, the ballistocardiogram andelectrocardiogram signals converted into the digital signals by the A/Dconverter.
 22. The scale-type nonconstrained health condition evaluatingapparatus according to claim 2, wherein the signal processor identifiesthe measured person through at least one of the calculated heart rate,normalized stroke volume force, blood pressure, equilibrium senseabnormality and weight of the measured person.
 23. The method accordingto claim 15, wherein the third calculating at least one of the heartrate comprises: amplifying the sensed ballistocardiogram andelectrocardiogram signals; filtering only necessary bands of theamplified ballistocardiogram and electrocardiogram signals; convertingthe filtered ballistocardiogram and electrocardiogram signals intodigital signals; and calculating at least one of the heart rate,normalized stroke volume force, blood pressure and equilibrium senseabnormality of the measured person from the weight of the measuredperson and the ballistocardiogram and electrocardiogram signalsconverted into the digital signals.
 24. The scale-type nonconstrainedhealth condition evaluating apparatus according to claim 21, wherein theband pass filter filters only 0.5 through 30 Hz components of theballistocardiogram signal amplified by the signal amplifier.
 25. Thescale-type nonconstrained health condition evaluating apparatusaccording to claim 21, wherein the band pass filter filters only 0.5through 35 Hz components of the electrocardiogram signal amplified bythe signal amplifier.
 26. The scale-type nonconstrained health conditionevaluating apparatus according to claim 21, wherein the computing unitdetects J waves from the ballistocardiogram signal converted by the A/Dconverter into the digital signal and calculates an interval of the Jwaves to obtain an average heart rate of the measured person.
 27. Thescale-type nonconstrained health condition evaluating apparatusaccording to claim 21, wherein the computing unit synchronizes theelectrocardiogram signal with the ballistocardiogram signal based on theJ waves of the ballistocardiogram signal to obtain an ensemble averageso as to generate averaged electrocardiogram and ballistocardiogramsignals.
 28. The scale-type nonconstrained health condition evaluatingapparatus according to claim 27, wherein the computing unit obtains themagnitude of the J waves from the averaged ballistocardiogram signal andcalculates the normalized stroke volume force of the measured personaccording to the following equation:Normalized stroke volume force=J-wave magnitude/weight
 29. Thescale-type nonconstrained health condition evaluating apparatusaccording to claim 27, wherein the computing unit detects an R-Jinterval from the averaged ballistocardiogram and electrocardiogramsignals and calculates the blood pressure of the measured person from aregression equation derived from data about correlation of the R-Jinterval and a systolic blood pressure.
 30. The scale-typenonconstrained health condition evaluating apparatus according to claim21, wherein the computing unit measures the extent of a variation of theballistocardiogram signal and determines whether the sense ofequilibrium of the measured person is abnormal from the measurementresult.